Question

This code produces an error in the GNU compiler:

class A
{
public:
    int X;
};

template<class T>
class Foo : public T
{
public:
    void doStuff();
};

template<class T>
void Foo<T>::doStuff()
{
    X++;
}

There is already an answer for why this is an error. I would like to know if there is another way of working around this error rather than using

T::X

every time I want to reference the X member. I tried this:

template<class T>
void Foo<T>::doStuff()
{
    using T::X;
    X++;
}

But GCC gives an error: “a class-qualified name is not allowed”

Answer 1

using T::X should work. If it gives error, there is some other problem with your code, or it must be compiler bug. See yourself : http://www.ideone.com/MI9fM

---

• You may use this pointer, as

  template<class T>
  void Foo<T>::doStuff()
  {
      this->X++;
  }
  

  This gives compiler a hint where to look for the symbol X.

Demo: http://www.ideone.com/NIucO

---

• You can also do this:

  template<class T>
  void Foo<T>::doStuff()
  {
       T::X++;
  }
  

Demo : http://www.ideone.com/PswvG